In medical care in recent years, medical treatments and tests in various forms have been conducted using thin, elongated, tubular medical instruments called catheters. As such therapeutic methods, procedures based on the use of a therapeutic catheter have been practiced utilizing the elongated nature of the catheter. Specific examples of such procedures include a method in which a medicine is administered directly to an affected part through a catheter, a method in which a stenosed (narrowed) part of a body lumen is forced open by use of a catheter equipped at its distal end with a balloon capable of being inflated by pressurization, a method in which a diseased part is cut away and opened by use of a catheter equipped with a cutter at a distal portion thereof, and a method in which, on the contrary, an aneurysm, a bleeding part or a nutrient vessel is closed by packing by use of a catheter. In addition, there is a therapeutic method in which a stent in the shape of a pipe with a meshed side surface is implanted and set indwelling in a body lumen by use of a catheter, for the purpose of keeping open a stenosed part of the body lumen. There are also cases where a thrombus obstructing a blood vessel is sucked away.
When conducting a treatment, test or the like by use of a catheter, in general, an introducer sheath is introduced into a puncture site in an arm or leg, by use of a catheter introducer, and a catheter or the like is percutaneously inserted into a lesion part of a blood vessel or the like through a lumen of the introducer sheath.
The introducer sheath is formed of a sheath tube, which is a tubular member having an inner cavity in which an elongated body such as a catheter can be inserted and passed. An example is U.S. Pat. No. 5,066,285. The introducer sheath has a distal portion which is located on the distal side at the time of introduction into a puncture part, and a main body section which is located on the proximal side of the distal portion.
In the case where a stenosis in an artery is found upon diagnosis of a patient's arteries and treatment is conducted in succession to the diagnosis, instead of conducting the treatment some other time, for example, the physical burden on the patient is heavy. In general, there is a tendency toward selection of a thinner diagnostic catheter in order to ensure lesser invasiveness and a tendency toward selection of a thicker therapeutic catheter and a thicker guiding catheter (for insertion of the therapeutic catheter) in order to permit appropriate execution of an intended procedure. In the case where a patient undergoes therapy following diagnosis, therefore, an introducer sheath having a small diameter used with a diagnostic catheter and having been inserted into the patient's artery has to be replaced by an introducer sheath having another size according for use with a therapeutic catheter. Set forth below is a description of a method for diagnosis and treatment of a coronary artery representing one example of the method for diagnosis and treatment of an artery.
Specifically, in a situation where a stenosis in a patient's artery is found upon diagnosis of the artery, it has been necessary to draw out an introducer sheath having been inserted in another artery or in another part of the same artery for introduction of a diagnostic catheter. After the drawing-out of the introducer sheath, it has been necessary to insert another introducer sheath with a larger inner diameter into the other artery or the other part of the same artery, for the purpose of introducing a therapeutic catheter into the patient's artery. For instance, in a situation where a stenosis in a patient's coronary artery is found upon diagnosis of the coronary artery, it has been necessary to draw out an introducer sheath which was previously inserted in the patient's radial artery or ulnar artery for introduction of a diagnostic catheter. After drawing-out the introducer sheath, it has been necessary to insert another introducer sheath with a larger inner diameter into the radial artery or ulnar artery, for the purpose of introducing a therapeutic catheter into the patient's coronary artery.
In this case, in the process of the patient undergoing diagnosis and treatment in succession, the two kinds of introducer sheaths differing in diameter are sequentially inserted into the patient's radial artery or ulnar artery. Such a procedure imposes a heavy physical burden on the patient.